"I'm a fan of yours, but also a long time supporter of Admiral Joe. I see you as two Bernies against the one corporate party machine candidate. I wish you could team up somehow," wrote the Redditor.

"We already have teamed up, as I am the only candidate that has endorsed Bernie Sanders for President," Fetterman replied. " In PA, I've got Bernie's back."

A Fetterman spokesperson furthered this in email, adding that his endorsement was unique not just for the state, but nationally: A January Philadelphia Inquirer article named the Braddock mayor as "the only statewide candidate nationally to endorse the Vermont senator."

Was that so? We were intrigued and decided to check it out.

Among Pennsylvania Democratic candidates for U.S. Senator, four people have declared for the April primary so far, and only Fetterman has endorsed Sanders. Katie McGinty, Gov. Tom Wolf’s former chief of staff, is endorsing Hillary Clinton. Sestak has declined to throw support officially behind Sanders or Clinton. In response to our inquiry, a Sestak spokesman repeated a statement previously given to other press: "Joe just focuses on the people of Pennsylvania so that he can continue to serve them." Wire and springs manufacturer Joseph Vodvarka from Clinton, Pa., told PolitiFact Pennsylvania that he’s yet to endorse anyone.

We looked for other Pennsylvania statewide candidates who endorsed Sanders and were unable to find any. So Fetterman’s comments on Reddit are accurate.

His spokesperson added that there are no other statewide candidates nationally who support Sanders, but we were able to find a few.

In Sanders’ home state of Vermont, for example, he has at least three such endorsers: former State Senator Matt Dunne, agubernatorial candidate; State Senator David Zuckerman, acandidate for lieutenant governor, and State Auditor Doug Hoffer, who is running to keep his office. In Iowa, Sanders supporter Tom Fiegen is running for U.S. Senate.

Still, Sanders has a notably low number of endorsements. Only two representatives in the U.S. Congress have endorsed Sanders, according to FiveThirtyEight, andno U.S. senators or governors have.

Bertram Johnson, a political science professor at Middlebury Collegeand expert in Vermont politics, said people endorse based on three factors:probability to win, their constituents’ leanings and political connections. "Endorsers are interested in someone who can support them and has supported them in the past, who’s been an insider for decades," Johnson explained. "This is obviously something that Bernie Sanders hasn’t done, because he hasn’t really been a Democrat until he entered this race."

"I don’t know that he has a longstanding national network among politicians," he continued. "I think what he’s done a good job of is using national media, like MSNBC, to cultivate support among liberal activists." Sanders’ high tally of small contributions and a long list of Hollywood endorsementsreflects this, Johnson said.

Our ruling

What answering questions about the Pennsylvania senate race, Fetterman said, "I am the only candidate that has endorsed Bernie Sanders for president. In PA, I've got Bernie's back." We found he is the only statewide candidate in Pennsylvania who has endorsed Sanders.

His office later claimed he was the only statewide candidate anywhere to endorse Sanders. That’s an exaggeration; statewide candidates in Vermont and Iowa have also endorsed Sanders.

We’re fact-checking Fetterman’s original claim, however, and that statement is accurate. We rate his statement True.

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